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Stuart L Pimm - One of the best experts on this subject based on the ideXlab platform.
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Elephant seasonal vegetation preferences across dry and wet savannas
Biological Conservation, 2009Co-Authors: Scott R Loarie, Stuart L Pimm, Rudi J Van AardeAbstract:As African savanna Elephants (Loxodonta africana) become increasingly confined to smaller fragmented landscapes, concern over their potential detrimental impacts on vegetation and biodiversity has increased. Understanding Elephant vegetation preferences across relevant spatial and temporal scales is a critical step towards managing protected areas for the persistence of both Elephants and biodiversity. To better understand Elephant vegetation selection, we fitted 68 Elephants with GPS collars across a strong rainfall gradient spanning seven southern African countries over a period of 6 years. We compared Elephant locations with remotely-sensed environmental data that measure bi-monthly vegetation greenness across the study area. Elephants consistently seek out greener than expected vegetation throughout the year. Interestingly, they do so by utilizing vegetation with different phenologies and by selecting landscapes when they are greener than their surroundings. We found no differences between dry and wet savannas. These patterns persist even when Elephants are constrained by seasonally available water. In the wet season, Elephants select seasonally variable landscapes such as open woodlands, shrublands, and grasslands. These landscapes have a lower average annual greenness but become very green for a few months in the wet season. In the dry season, Elephants prefer less variable landscapes that are more consistently green year-round such as well-wooded areas and closed woodlands. Because Elephants prefer different vegetation types at different times of the year, small homogeneous protected areas may be unsuitable for Elephants. Since Elephants prefer woody vegetation during the dry season when they are constrained by water, human actions that increase dry season water availability may contribute to detrimental Elephant impacts on vegetation and biodiversity.
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rules of habitat use by Elephants loxodonta africana in southern africa insights for regional management
Oryx, 2008Co-Authors: Grant Harris, Gareth J Russell, Rudi I Van Aarde, Stuart L PimmAbstract:Managers in southern Africa are concerned that continually increasing Elephant populations will degrade ecosystems. Culling, translocation and birth control are flawed solutions. An alternative is providing Elephants more space but this hinges on identifying landscape preferences. We examined two diverse eco- systems and uncovered similarities in Elephant habitat use, expressing these as 'rules'. We considered arid Etosha National Park, (Namibia) and the tropical wood- lands of Tembe Elephant Park (South Africa) and Maputo Elephant Reserve (Mozambique). Landscape data con- sisted of vegetation types, distances from water and settlements. To surmount issues of scale and availability we incorporated Elephant movements as a function that declined as distance from an Elephant's location in- creased. This presumes that Elephants optimize trade- offs between benefiting from high-quality resources and costs to find them. Under a likelihood-based approach we determined the important variables and shapes of their relationships to evaluate and compare models separated by gender, season and location. After consid- ering Elephants' preferences for areas nearby, habitat use usually increased with proximity to water in all loca- tions. Elephants sought places with high proportions of vegetation, especially when neighbouring areas had low vegetative cover. Lastly, Elephants avoided human set- tlements (when present), and cows more so than bulls. In caricature, Elephants preferred to move little, drink easily, eat well, and avoid people. If one makes more areas available, Elephants will probably favour areas near water with high vegetative cover (of many different types) and away from people. Managers can oblige Elephants' preferences by supplying them. If so, they should anticipate higher impacts to neighbouring vegetation.
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rules of habitat use by Elephants loxodonta africana in southern africa insights for regional management
Oryx, 2008Co-Authors: Grant Harris, Gareth J Russell, Rudi I Van Aarde, Stuart L PimmAbstract:Managers in southern Africa are concerned that continually increasing Elephant populations will degrade ecosystems. Culling, translocation and birth control are flawed solutions. An alternative is providing Elephants more space but this hinges on identifying landscape preferences. We examined two diverse eco- systems and uncovered similarities in Elephant habitat use, expressing these as 'rules'. We considered arid Etosha National Park, (Namibia) and the tropical wood- lands of Tembe Elephant Park (South Africa) and Maputo Elephant Reserve (Mozambique). Landscape data con- sisted of vegetation types, distances from water and settlements. To surmount issues of scale and availability we incorporated Elephant movements as a function that declined as distance from an Elephant's location in- creased. This presumes that Elephants optimize trade- offs between benefiting from high-quality resources and costs to find them. Under a likelihood-based approach we determined the important variables and shapes of their relationships to evaluate and compare models separated by gender, season and location. After consid- ering Elephants' preferences for areas nearby, habitat use usually increased with proximity to water in all loca- tions. Elephants sought places with high proportions of vegetation, especially when neighbouring areas had low vegetative cover. Lastly, Elephants avoided human set- tlements (when present), and cows more so than bulls. In caricature, Elephants preferred to move little, drink easily, eat well, and avoid people. If one makes more areas available, Elephants will probably favour areas near water with high vegetative cover (of many different types) and away from people. Managers can oblige Elephants' preferences by supplying them. If so, they should anticipate higher impacts to neighbouring vegetation.
Prithiviraj Fernando - One of the best experts on this subject based on the ideXlab platform.
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Problem-Elephant Translocation: Translocating the Problem and the Elephant?
PloS one, 2012Co-Authors: Prithiviraj Fernando, Peter Leimgruber, Tharaka Prasad, Jennifer PastoriniAbstract:Human-Elephant conflict (HEC) threatens the survival of endangered Asian Elephants (Elephas maximus). Translocating “problem-Elephants” is an important HEC mitigation and Elephant conservation strategy across Elephant range, with hundreds translocated annually. In the first comprehensive assessment of Elephant translocation, we monitored 16 translocations in Sri Lanka with GPS collars. All translocated Elephants were released into national parks. Two were killed within the parks where they were released, while all the others left those parks. Translocated Elephants showed variable responses: “homers” returned to the capture site, “wanderers” ranged widely, and “settlers” established home ranges in new areas soon after release. Translocation caused wider propagation and intensification of HEC, and increased Elephant mortality. We conclude that translocation defeats both HEC mitigation and Elephant conservation goals.
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perceptions and patterns of human Elephant conflict in old and new settlements in sri lanka insights for mitigation and management
Biodiversity and Conservation, 2005Co-Authors: Prithiviraj Fernando, Devaka Weerakoon, Eric Wikramanayake, L K A Jayasinghe, Manori Gunawardene, H K JanakaAbstract:Human–Elephant conflict poses a major threat to Elephants in many parts of Asia, including Sri Lanka. We studied human–Elephant conflict in two areas with contrasting scenarios of landuse and conflict, Kahalle and Yala. Kahalle was developed and settled under the Mahaweli irrigation project and the main agricultural practice was irrigated agriculture, with two annual growing seasons. The area was a mosaic of settlements, agriculture, and small forest patches with ill defined human- and Elephant-use areas. Elephants ranged within the habitat mosaic year round, occupying remnant forest patches and raiding adjacent crops at night. In contrast, Yala was dominated by a large protected area complex, and the main agricultural methods were slash-and-burn agriculture and rain-fed paddy cultivation. Human- and Elephant-use areas were well defined and segregated. The protected area provided Elephants with a refuge and food during the rainy season, when the single annual crop was grown. During the dry season, Elephants moved into slash-and-burn areas and utilized leftover crops and pioneer vegetation in fallow fields. The landuse pattern and agricultural practices in Yala facilitated co-existence, whereas that in Kahalle led to year round conflict. We suggest that areas managed according to traditional landuse practices should be part of an Elephant conservation strategy, where people and Elephants have to share resources.
Simon L. Lewis - One of the best experts on this subject based on the ideXlab platform.
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The Role of Forest Elephants in Shaping Tropical Forest–Savanna Coexistence
Ecosystems, 2019Co-Authors: Anabelle W. Cardoso, Yadvinder Malhi, Imma Oliveras, David Lehmann, Josué Edzang Ndong, Edmond Dimoto, Emma Bush, Kathryn Jeffery, Nicolas Labriere, Simon L. LewisAbstract:Forest edges that border savanna are dynamic features of tropical landscapes. Although the role of fire in determining edge dynamics has been relatively well explored, the role of mega-herbivores, specifically Elephants, has not received as much attention. We investigated the role of forest Elephants in shaping forest edges of the forest–savanna mosaic in Lopé National Park, Gabon. Using forty camera traps, we collected 1.2 million images between May 2016 and June 2017. These images were classified by over 10,000 volunteers through an online citizen science platform. These data were combined with a 33-year phenology dataset on Elephant-favoured fruiting tree species, and field measurements of Elephant browsing preferences and damage. Our results showed a strong relationship between forest Elephant density at the forest edge and fruit availability. When fruit availability was high, Elephant density at the edge reached values nearly double the highest densities ever reported in any other part of the landscape (7.5 Elephants km^−2 in this study vs the previous highest estimate of 4 Elephants km^−2). The highest Elephant densities occurred at the end of the dry season, but even outside of this high density period Elephant density at the forest edge (2.4 Elephants km^−2) was more than double what other studies estimate for forest interiors with low human hunting pressure (1 Elephant km^−2). We found forest Elephants to be selective browsers, but their browsing was non-destructive (in contrast to savanna Elephants) and had little effect on tree size demography. Elephant paths acted as firebreaks during savanna burning, making them inadvertent protectors of the fire-sensitive forest and contributing to the stabilising feedbacks that allow forest and savanna to coexist in tropical landscapes.
Alfred L Roca - One of the best experts on this subject based on the ideXlab platform.
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Development and characterization of microsatellite markers in the African forest Elephant ( Loxodonta cyclotis )
BMC Research Notes, 2016Co-Authors: Natalie A. Gugala, Nicholas J Georgiadis, Yasuko Ishida, Alfred L RocaAbstract:Background African Elephants comprise two species, the savanna Elephant (Loxodonta africana) and the forest Elephant (L. cyclotis), which are distinct morphologically and genetically. Forest Elephants are seriously threatened by poaching for meat and ivory, and by habitat destruction. However, microsatellite markers have thus far been developed only in African savanna Elephants and Asian Elephants, Elephas maximus. The application of microsatellite markers across deeply divergent lineages may produce irregular patterns such as large indels or null alleles. Thus we developed novel microsatellite markers using DNA from two African forest Elephants.
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genomic dna sequences from mastodon and woolly mammoth reveal deep speciation of forest and savanna Elephants
PLOS Biology, 2010Co-Authors: Nadin Rohland, Nicholas J Georgiadis, Alfred L Roca, Matthias Meyer, Richard E Green, Swapan Mallick, David Reich, Michael HofreiterAbstract:To elucidate the history of living and extinct Elephantids, we generated 39,763 bp of aligned nuclear DNA sequence across 375 loci for African savanna Elephant, African forest Elephant, Asian Elephant, the extinct American mastodon, and the woolly mammoth. Our data establish that the Asian Elephant is the closest living relative of the extinct mammoth in the nuclear genome, extending previous findings from mitochondrial DNA analyses. We also find that savanna and forest Elephants, which some have argued are the same species, are as or more divergent in the nuclear genome as mammoths and Asian Elephants, which are considered to be distinct genera, thus resolving a long-standing debate about the appropriate taxonomic classification of the African Elephants. Finally, we document a much larger effective population size in forest Elephants compared with the other Elephantid taxa, likely reflecting species differences in ancient geographic structure and range and differences in life history traits such as variance in male reproductive success.
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genetic evidence for two species of Elephant in africa
Science, 2001Co-Authors: Alfred L Roca, Nicholas J Georgiadis, Jill Peconslattery, Stephen J ObrienAbstract:Elephants from the tropical forests of Africa are morphologically distinct from savannah or bush Elephants. Dart-biopsy samples from 195 free-ranging African Elephants in 21 populations were examined for DNA sequence variation in four nuclear genes (1732 base pairs). Phylogenetic distinctions between African forest Elephant and savannah Elephant populations corresponded to 58% of the difference in the same genes between Elephant genera Loxodonta (African) and Elephas (Asian). Large genetic distance, multiple genetically fixed nucleotide site differences, morphological and habitat distinctions, and extremely limited hybridization of gene flow between forest and savannah Elephants support the recognition and conservation management of two African species: Loxodonta africana and Loxodonta cyclotis.
Anabelle W. Cardoso - One of the best experts on this subject based on the ideXlab platform.
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The Role of Forest Elephants in Shaping Tropical Forest–Savanna Coexistence
Ecosystems, 2019Co-Authors: Anabelle W. Cardoso, Yadvinder Malhi, Imma Oliveras, David Lehmann, Josué Edzang Ndong, Edmond Dimoto, Emma Bush, Kathryn Jeffery, Nicolas Labriere, Simon L. LewisAbstract:Forest edges that border savanna are dynamic features of tropical landscapes. Although the role of fire in determining edge dynamics has been relatively well explored, the role of mega-herbivores, specifically Elephants, has not received as much attention. We investigated the role of forest Elephants in shaping forest edges of the forest–savanna mosaic in Lopé National Park, Gabon. Using forty camera traps, we collected 1.2 million images between May 2016 and June 2017. These images were classified by over 10,000 volunteers through an online citizen science platform. These data were combined with a 33-year phenology dataset on Elephant-favoured fruiting tree species, and field measurements of Elephant browsing preferences and damage. Our results showed a strong relationship between forest Elephant density at the forest edge and fruit availability. When fruit availability was high, Elephant density at the edge reached values nearly double the highest densities ever reported in any other part of the landscape (7.5 Elephants km^−2 in this study vs the previous highest estimate of 4 Elephants km^−2). The highest Elephant densities occurred at the end of the dry season, but even outside of this high density period Elephant density at the forest edge (2.4 Elephants km^−2) was more than double what other studies estimate for forest interiors with low human hunting pressure (1 Elephant km^−2). We found forest Elephants to be selective browsers, but their browsing was non-destructive (in contrast to savanna Elephants) and had little effect on tree size demography. Elephant paths acted as firebreaks during savanna burning, making them inadvertent protectors of the fire-sensitive forest and contributing to the stabilising feedbacks that allow forest and savanna to coexist in tropical landscapes.